GarageBoy
Flashlight Enthusiast
Now that lights like the EZAA can do low lumen work with even better efficiency (brighter than my Inova X1 and runs longer?) is there any reason left to go with 5mms?
Any advantages that 5mm LEDs have over power LEDs?
- Thread starter GarageBoy
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Sgt. LED
Flashaholic
They are really cheap.
They can be treated much rougher.
They can be treated much rougher.
SilentK
Enlightened
Well, most of them have very good runtimes from my experience. they make very good "mag candles"
GarageBoy
Flashlight Enthusiast
Actually, is my statement correct that power LEDs are more efficient, even at lower drive levels?
Illum
Flashaholic
uber-efficient at 15ma, CREEs suck below 150ma
Personally I prefer 5mms in total darkness, because anything over ~15 lumens is overkill, at least to me
Personally I prefer 5mms in total darkness, because anything over ~15 lumens is overkill, at least to me
Marduke
Flashaholic
XR-E efficiency is supreme at 20 mA constant current. Only plus of 5mm's is ability to be driven CC below that, and price.
You can get unbeatable efficiency driving high flux at 20mA CC plus PWM lower.
Illum
Flashaholic
Didn't seem that bright when I tried running 2 XR-E P4 at 25ma each :thinking:
I've made a dual P4 gooseneck light off USB but I had to keep it around 50ma for it to look bright enough
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WadeF
Flashlight Enthusiast
Most of the Fenix lights, like the P2D, run the XR-E at around 25mA on low. 20-25mA is the sweet spot for efficiency with XR-E's. As you increase current the efficiency goes down.
DM51
Flashaholic
This thread is principally to do with the characteristics of different LED types, rather than the lights that use them, so I'm moving it from LED Flashlights to LED.
vali
Enlightened
Uhm... Im not sure. Just check (real) lumen/runtime of E01 vs LD01. I think nowadays 5 mm are a bit more efficient at about 20 mA, but powerleds are catching them up.
BTW I am just remembering some tests I read in the forums, but maybe my memory is flawed :shrug:. There is a thread with efficient charts but they are not too big/detailed to use as "fact" at low currents.
BTW I am just remembering some tests I read in the forums, but maybe my memory is flawed :shrug:. There is a thread with efficient charts but they are not too big/detailed to use as "fact" at low currents.
clg0159
Enlightened
Well, the efficiency is better, but you still have the XR-E's 90deg viewing angle vs the 15 or 30 of a 5mm... but at least you don't have to look at that angy blue light:sick2:
Marduke
Flashaholic
High flux absolutely smashes 5mm's at ~20mA, which is a rather high current for 5mm's. The XR-E R2's are ~145 lm/w at ~20mA.
jtr1962
Flashaholic
For flashlights or general lighting, 5mm LEDs have no advantage at all but many disadvantages (generally shorter life, usually lower efficiency). Where they excel is where you only need a small amount of light, or perhaps need the light distributed, or where cost is a factor. As good an example of any is my project to light HO passenger cars. To distribute the light evenly I needed at least 3 or 4 LEDs. While power LEDs would have worked for that this was a cost-sensitive project. 4 5mm LEDs might cost $0.50. Power LEDs cost at least $2.50 each, even in quantity. So that's $10 versus $0.50. In this app efficiency didn't matter much. I underdrove the LEDs so I was getting perhaps 50 or 55 lm/W (didn't use the most efficient 5mms either for cost and tint reasons). I might have doubled that or more with power LEDs but the power savings were unimportant. There weren't any heat problems either (total power dissipation was about 1/4 watt IIRC) even with the less efficient LEDs. Lifetime being underdriven will probably be at least 10,000 hours-more than good enough for this application. Bottom line-this was an application for which power LEDs would have made zero sense. Same if I make HO-scale street lights or light up structures. I need a lot of small light sources for good effect. Each one may only be 1 or 2 lumens, perhaps way less. 5mm or 3mm or PLCC or other types of smaller, low-power LEDs are ideally suited to projects like this. Just as you wouldn't use a 1000 watt HID stadium light in your bathroom, sometimes power LEDs are just plain overkill.
vali
Enlightened
The my memory is failing me
. I said that because I thought I read it somewhere in the forums and because almost all small flashlights with loooong runtime use some sort of 5/3 mm white leds.I was planning making a 2D "extreme" runtime flashlight a while ago and almost asked a similar question (wich is better, 2x5mm @ 10 mAh or a high-flux @ 20?).
Does anyone have some detailed charts of high-flux leds between 0-50 mAh?
Marduke
Flashaholic
http://www.candlepowerforums.com/vb/showthread.php?t=89607
The LONG runtimes of 5mm lights is due to the low current used. This low current is artificially imposed by the rather low required drive current of the 5mm's. You could get the same runtime with more brightness from a high flux driven at the same current.
vali
Enlightened
Thanks for the link. I was aware of those charts, but with powerleds they are too wide (in the sense they cover from 0 to 1+ A). I'm interested only in the low current zone. Charts like the 3/5 mm ones but with powerleds (only showing the first 100 mA) will be really usefull to compare side by side both types of leds. Right now you can guess somewhere between 0 and 50 is the efficiency peak but you cant say it accurately.
It seems the efficiency peak is about 25 mA or so for P4. My memory was telling me it was about 50 mA and, because efficiency drops very fast with less than optimal current, thought at 20 mA 5mm leds had the advantage. So I was VERY wrong. Shame on me for not checking that thread before replying here.
Another advantage is that 5mm LEDs don't need additional optics, they are usually focussed at around 10° to 30°, while power LEDs have a wider viewing angle which needs an extra reflector or lens to make a concentrated light beam.
I'm not a fan of 5mm LEDs anymore since you never know what you get with cheap ones and good ones are quite expensive (Nichia). Plus efficacy is lower than power LEDs and the color rendition is usually worse (very blue/purple tinted).
I'm not a fan of 5mm LEDs anymore since you never know what you get with cheap ones and good ones are quite expensive (Nichia). Plus efficacy is lower than power LEDs and the color rendition is usually worse (very blue/purple tinted).
Illum
Flashaholic
well..remember that it heatsinks through the wires...so if you can, use a low gauge wire as close to the LED as possible. :nana:
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